The foster carers of the Parsons Green bomber are taking legal action against the council that placed him in their home.
Iraqi teenage asylum seeker Ahmed Hassan, who pretended to engage with the anti-terrorism Prevent scheme as he plotted mass murder in London, was sentenced to life with a minimum term of 34 years at the Old Bailey last year.
Hassan's foster parents Penny and Ron Jones, who were awarded an MBE in 2010, are suing Surrey County Council, claiming that the council presented him "merely as a troubled young person" and did not disclose key information about the danger he posed.
The teenager, who lived in Sunbury, Surrey, made a bomb with 400g of "Mother of Satan" explosives and 2.2kg of shrapnel while his unsuspecting foster carers were on holiday in Blackpool.
The bomb injured 51 passengers on September 15 2017.
His trial heard how Hassan arrived in Britain illegally in 2015 and told officials he had trained with Islamic State (IS).
Mr and Mrs Jones, who fostered 269 children in 47 years, say they have been "betrayed" and "hung out to dry" by Surrey County Council, as they have not been asked to foster any more children since Hassan's arrest.
Mrs Jones, 72, said: "We want to make sure that no other foster carers are ever treated like we have been."
The couple are claiming that the council was negligent in not telling them the full story about Hassan's past and that they breached their right to family life as protected under the Human Rights Act.
Mrs Jones said: "They told me that he had tried to kill himself and would only be released if he was fostered into a stable home so we took him in.
"On the surface he was a lovely boy. He wouldn't let Ron mow the lawn and he would always carry the shopping in from the car. So when it came out he was building a bomb in our home it was a real shock."
Mr Jones said: "We were told that the amount of explosives he had was enough to blow up this entire block of six houses. It's terrifying."